I came up with this recipe a couple years ago and its awesome for grilling a backstrap. Best on Sika deer (elk), but good for WT too.
1/2 cup Olive oil
1/2 cup soy sauce.
1/4cup worchestershire sauce.
Hot sauce to taste.
Excessive amounts of chopped garlic (advise against substituting garlic powder).
Heavy dose of cumin.
Don't marinade for too long... 20 minutes is enough. Get plenty of garlic on the meat and cook it hot and fast on a charcoal grill for best flavor.